Why is it not showing all the data?

Issue

I am creating this app which shows the latest news, which gets data from https://newsapi.org/s/india-health-news-api but it doesn't fetch all the data. Sometimes it just shows all but sometimes it just shows 2 or 3 news. Also, I don't see any log error message. What is the problem?

HealthNews.java

public class HealthNews extends AppCompatActivity {
private ArrayList urlList;
private NewsAdapter mNewsAdapter;

private static final String REQUEST_URL ="https://newsapi.org/v2/top-headlines?country=in&category=health&apiKey=3f7d99cdbb004766892bd239a4c099be";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_health_news);

    Intent intent = getIntent();
    HealthNews.NewsAsyncTask task = new HealthNews.NewsAsyncTask();
    task.execute(REQUEST_URL);

    urlList = QueryUtils.m;

    ListView listView = (ListView)findViewById(R.id.listViewHealthNews);

    mNewsAdapter = new NewsAdapter(this, new ArrayList<News>());
    listView.setAdapter(mNewsAdapter);

    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

            //Toast.makeText(getApplicationContext(), ""+ a.get(position), Toast.LENGTH_SHORT).show();

            Object url = urlList.get(position);
            Uri uri = (Uri) Uri.parse((String) url); // missing 'http://' will cause crashed
            Intent intent = new Intent(Intent.ACTION_VIEW, uri);
            startActivity(intent);

        }
    });
}

private class NewsAsyncTask extends AsyncTask<String, Void, ArrayList<News>> {
    ProgressDialog p;

    @Override
    protected ArrayList<News> doInBackground(String... urls) {
        if (urls.length < 1 || urls[0] == null) {
            return null;
        }

        ArrayList<News> result = QueryUtils.fetchEarthquakeData(urls[0]);
        return result;
        //return null;
    }

    @Override
    protected void onPostExecute(ArrayList<News> data) {
        mNewsAdapter.clear();

        if (data != null && !data.isEmpty()) {
            p.hide();
            mNewsAdapter.addAll(data);
        }
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        p = new ProgressDialog(HealthNews.this);
        p.setMessage("Latest News...");
        p.setIndeterminate(false);
        p.show();
    }

}
}

QueryUtils.java

private static final String LOG_TAG = "";

private QueryUtils(){
}

private static URL createUrl(String stringUrl) {
    URL url = null;
    try {
        url = new URL(stringUrl);
    } catch (MalformedURLException e) {
        Log.e(LOG_TAG, "Problem building the URL ", e);
    }
    return url;
}

private static String makeHttpRequest(URL url) throws IOException {
    String jsonResponse = "";

    // If the URL is null, then return early.
    if (url == null) {
        return jsonResponse;
    }

    HttpURLConnection urlConnection = null;
    InputStream inputStream = null;
    try {
        urlConnection = (HttpURLConnection) url.openConnection();
        urlConnection.setReadTimeout(30000 /* milliseconds */);
        urlConnection.setConnectTimeout(60000 /* milliseconds */);
        urlConnection.setRequestMethod("GET");
        urlConnection.connect();

        if (urlConnection.getResponseCode() == 200) {
            inputStream = urlConnection.getInputStream();
            jsonResponse = readFromStream(inputStream);
        } else {
            Log.e(LOG_TAG, "Error response code: " + urlConnection.getResponseCode());
        }
    } catch (IOException e) {
        Log.e(LOG_TAG, "Problem retrieving the earthquake JSON results.", e);
    } finally {
        if (urlConnection != null) {
            urlConnection.disconnect();
        }
        if (inputStream != null) {
            inputStream.close();
        }
    }
    return jsonResponse;
}

private static String readFromStream(InputStream inputStream) throws IOException {
    StringBuilder output = new StringBuilder();
    if (inputStream != null) {
        InputStreamReader inputStreamReader = new InputStreamReader(inputStream, Charset.forName("UTF-8"));
        BufferedReader reader = new BufferedReader(inputStreamReader);
        String line = reader.readLine();
        while (line != null) {
            output.append(line);
            line = reader.readLine();
        }
    }
    return output.toString();
}

static ArrayList<String> m = new ArrayList<String>();

public static ArrayList<News> extractNews(String SAMPLE_JSON){
    if (TextUtils.isEmpty(SAMPLE_JSON)) {
        return null;
    }

    ArrayList<News> news = new ArrayList<News>();
    try {

        JSONObject jsonObject1 = new JSONObject(SAMPLE_JSON);
        JSONArray baseJSONArray = jsonObject1.getJSONArray("articles");

        for (int i = 0; i < baseJSONArray.length(); i++) {
            JSONObject jsonObject = baseJSONArray.getJSONObject(i);
            JSONObject source = jsonObject.getJSONObject("source");

            String name = source.getString("name");
            String article = jsonObject.getString("title");
            String url1 = jsonObject.getString("url");
            String img = jsonObject.getString("urlToImage");
            URL url = new URL(img);
            Bitmap image = BitmapFactory.decodeStream(url.openConnection().getInputStream());

            News a = new News(image, article);
            news.add(a);
            m.add(url1);
        }
    } catch (JSONException j) {

    } catch (MalformedURLException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
    return news;
}
public static ArrayList<News> fetchEarthquakeData(String requestUrl) {
    URL url = createUrl(requestUrl);

    String jsonResponse = null;
    try {
        jsonResponse = makeHttpRequest(url);
    } catch (IOException e) {
        Log.e(LOG_TAG, "Problem making the HTTP request.", e);
    }

    ArrayList<News> news = extractNews(jsonResponse);

    return news;
}

Solution

I went though your code and found some issues.

Some bad practices i found in your code are:

1. You are adding your urls in separate list with static specifier. Instead of this you should add the url variable in your News model directly. And you can directly retrieve the whole News model inside ListView > setOnItemClickListener.
2. You are creating Bitmap for all your images. It may cause OOM Exception. You should use any Image loading library instead.

I have fixed that all issues and created working code. Please do required changes which you want at your end.

HealthNews.java

public class HealthNews extends AppCompatActivity {

    private Context context;
    private NewsAdapter mNewsAdapter;

    private ArrayList<News> listNews;

    private static final String REQUEST_URL = "https://newsapi.org/v2/top-headlines?country=in&category=health&apiKey=3f7d99cdbb004766892bd239a4c099be";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.health_news);

        context = this;

        ListView list_news = findViewById(R.id.list_news);

        listNews = new ArrayList<>();

        mNewsAdapter = new NewsAdapter(context, listNews);
        list_news.setAdapter(mNewsAdapter);

        list_news.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                try {
                    News selNews = (News) parent.getAdapter().getItem(position);
                    startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse(selNews.getUrl())));
                } catch (Exception e) {
                    // Missing 'http://' or 'https://' will cause crash
                    e.printStackTrace();
                }
            }
        });

        new NewsAsyncTask().execute(REQUEST_URL);
    }

    private class NewsAsyncTask extends AsyncTask<String, Void, ArrayList<News>> {

        private ProgressDialog p;

        @Override
        public void onPreExecute() {
            super.onPreExecute();
            p = new ProgressDialog(context);
            p.setMessage("Latest News...");
            p.setIndeterminate(false);
            p.show();
        }

        @Override
        public ArrayList<News> doInBackground(String... urls) {
            return QueryUtils.fetchEarthquakeData(urls[0]);
        }

        @Override
        public void onPostExecute(ArrayList<News> newsList) {
            super.onPostExecute(newsList);
            listNews.addAll(newsList);
            p.hide();
            mNewsAdapter.notifyDataSetChanged();
        }
    }
}

QueryUtils.java

public class QueryUtils {

    public static ArrayList<News> fetchEarthquakeData(String apiUrl) {

        ArrayList<News> listNews = new ArrayList<>();

        try {

            URL url = new URL(apiUrl);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setReadTimeout(30000);
            conn.setConnectTimeout(60000);
            conn.setRequestMethod("GET");
            conn.connect();

            int responseCode = conn.getResponseCode();

            InputStream iStream;

            if (responseCode == HttpURLConnection.HTTP_OK)
                iStream = conn.getInputStream();
            else
                iStream = conn.getErrorStream();

            BufferedReader br = new BufferedReader(new InputStreamReader(iStream));

            StringBuilder response = new StringBuilder();

            String line;

            while ((line = br.readLine()) != null) {
                response.append(line);
            }

            String jsonResponse = response.toString();

            if (TextUtils.isEmpty(jsonResponse))
                return null;

            JSONObject jsonObject1 = new JSONObject(jsonResponse);
            JSONArray baseJSONArray = jsonObject1.getJSONArray("articles");

            for (int i = 0; i < baseJSONArray.length(); i++) {

                JSONObject jsonObject = baseJSONArray.getJSONObject(i);
                JSONObject source = jsonObject.getJSONObject("source");

                News news = new News();
                news.setArticle(jsonObject.optString("title"));
                news.setUrl(jsonObject.optString("url"));
                news.setUrlToImage(jsonObject.optString("urlToImage"));

                listNews.add(news);
            }
        } catch (JSONException e) {
            e.printStackTrace();
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return listNews;
    }
}

News.java (Model)

public class News {

    private String article;
    private String url;
    private String urlToImage;

    public News() {
        this.article = "";
        this.url = "";
        this.urlToImage = "";
    }

    public String getArticle() {
        return article;
    }

    public void setArticle(String article) {
        this.article = article;
    }

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    public String getUrlToImage() {
        return urlToImage;
    }

    public void setUrlToImage(String urlToImage) {
        this.urlToImage = urlToImage;
    }
}

NewsAdapter.java (Change your item layout as per your code)

public class NewsAdapter extends BaseAdapter {

    private Context context;
    private LayoutInflater mInflater;

    private List<News> listNews;

    public NewsAdapter(Context context, List<News> listNews) {

        this.context = context;
        this.listNews = listNews;

        mInflater = LayoutInflater.from(context);
    }

    @Override
    public int getCount() {
        return listNews.size();
    }

    @Override
    public News getItem(int position) {
        return listNews.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    private class ViewHolder {
        private ImageView item_img_news;
        private TextView item_txt_article;
    }

    @SuppressLint("InflateParams")
    @Override
    public View getView(final int position, View convertView, ViewGroup parent) {

        final ViewHolder holder;

        if (convertView == null) {

            convertView = mInflater.inflate(R.layout.item_news, null);

            holder = new ViewHolder();

            holder.item_img_news = convertView.findViewById(R.id.item_img_news);
            holder.item_txt_article = convertView.findViewById(R.id.item_txt_article);

            convertView.setTag(holder);

        } else {
            holder = (ViewHolder) convertView.getTag();
        }

        final News news = getItem(position);

        holder.item_txt_article.setText(news.getArticle());

        Glide.with(context).load(news.getUrlToImage()).into(holder.item_img_news);

        return convertView;
    }
}

app > build.gradle

implementation 'com.github.bumptech.glide:glide:4.9.0'

Answered By - Ajay Mehta